Wireless communication systems are widely deployed to provide various types of communication content such as voice, data, and so on. These systems may be multiple-access systems capable of supporting communication with multiple users by sharing the available system resources (e.g., bandwidth and transmit power). Examples of such multiple-access systems include code division multiple access (CDMA) systems, time division multiple access (TDMA) systems, frequency division multiple access (FDMA) systems, 3GPP Long Term Evolution (LTE) systems, and orthogonal frequency division multiple access (OFDMA) systems.
Generally, a wireless multiple-access communication system can simultaneously support communication for multiple wireless terminals. Each terminal communicates with one or more base stations via transmissions on the forward and reverse links. The forward link (or downlink) refers to the communication link from the base stations to the terminals, and the reverse link (or uplink) refers to the communication link from the terminals to the base stations. This communication link may be established via a single-in-single-out, multiple-in-single-out or a multiple-in-multiple-out (MIMO) system.
In wireless communication systems, impedance matching may be required to optimize energy transfer from a source to a load in radio-frequency (RF) circuits. One of the more challenging applications for impedance matching is between a transmitter as a source and an antenna as a load. A poor impedance match results in the inefficient transfer of power to the antenna. As a result, transmit power may need to be increased to compensate, reducing battery life in mobile devices. Similarly, mismatch between an antenna as a source and a receiver as a load results in reduced received signal quality-albeit with less impact on power consumption. Antenna matching becomes even more challenging in wireless devices that utilize multiple antennas designed to support a wide range of air interfaces and operating bands.